It was the biggest art theft in the Netherlands since 20 works disappeared from Amsterdam's Van Gogh museum in 1991.

Three suspects have been detained at the request of prosecutors from the Romanian Directorate for Investigating Organised Crime and Terrorism (DIICOT), the Romanian Mediafax news agency reports.

Rotterdam police spokeswoman Yvette van den Heerik confirmed the arrests, adding that the suspects' involvement in the heist was still being investigated,

The robbery took place before daybreak on 16 October last year.

Police were alerted during the night when the gallery's state-of-the-art alarm system went off but the thieves had already left the premises by the time officers arrived at the scene.

Experts estimate the items taken could be worth "hundreds of millions of euros" if sold legally at auction. But this is unlikely, seeing as the seven paintings have been registered internationally as stolen.